[Mesa-dev] [PATCH v2 6/7] radeonsi: Add DCC decompress.

[Axel Davy]

On 12/10/2015 17:05, Bas Nieuwenhuizen wrote:
> Hi Marek,
>
> Thanks for the quick review.
>
> I do not think I understand the sharing semantics. We currently have
> fast clear for scanout surfaces with the CMASK and eliminate it on
> flush resource. I would think we could do that similarly with DCC fast
> clear. Both require a flush_resource after modifying the resource
> before other applications can use it.
>
> Furthermore, if we disable DCC for image stores, we also need to
> communicate that. We could leave DCC enabled for sampling as long as
> the DCC buffer stays in decompressed state. But we would need to
> communicate that DCC should not be used anymore for rendering.
>
> Do we still want patch 6 and 7 or should I drop them until we have an
> actual user?
>
> Yours sincerely,
> Bas Nieuwenhuizen
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Hi,

I think it would be better perf wise to not disable DCC for the 
backbuffer (which
is both shared and scanout currently). Decompressing anything that needs 
to be decompressed
in flush_resource seems to me a good idea.

For dx9 apps, it seems the applications do render a lot of draw calls to 
the backbuffer directly.
Likely having the backbuffer compressed with DCC (after it's been 
cleared), and then decompressing
before sending it should - I guess - be faster than keeping it uncompressed.
I don't know for gl apps, but I guess it's the same than dx9.

I tested the current serie, and it seems to boost some apps.

Yours,

Axel